runtime/bin/vmservice/client/lib/src/elements/json_view.html

<link rel="import" href="nav_bar.html">
<link rel="import" href="observatory_element.html">
<polymer-element name="json-view" extends="observatory-element">
  <template>
    <nav-bar>
      <top-nav-menu last="{{ true }}"></top-nav-menu>
    </nav-bar>
      <pre>{{ mapAsString }}</pre>
  </template>
  <script type="application/dart" src="json_view.dart"></script>
</polymer-element>